Homogenizing apparatus



July 20, 1965 w, MQULD, JR 3,195,867

HOMOGENIZING APPARATUS Filed Jan. 23, 1962 2 Sheets-Sheet J L nmmh FIG. 4

IN V EN TOR.

HARRY W. MOULD, JR.

ATTORNEY r July 20, 1965 H. w. MOULD, JR 3,195,867

HOMOGENIZING APPARATUS Filed Jan. 23, 1962 2 Sheets-Sheet 2 INVENTOR.

HARY W. MOULD, JR.

ATTORNEY i United States Patent 3,195,867 HOMOGENIZING APPARATUS Harry W. Mould, J12, llufialo, N.Y., assignor, by mesne assignments, to Liberty National Bank and Trust Company, Bufialo, N.Y., a national banking association Filed Jan. 23, 1962, Ser. No. 168,142 (Claims. (Cl. 259-9) This invention relates to homogenizing fluids, and more particularly to apparatus for homogenizing and blending milk, oil, fruit slurries, etc.

Most known homogenizing apparatus may be generally classified as either batch type, or continuous-flow type. In the former, a quantity of fluid is placed in an open tank and beat or mixed by means of a rotating paddle or agitator which is immersed in the fluid. The tank has usually to be rather large so that a substantial batch or quantity of fluid may be subjected to the rotating paddle or agitator at one time. However, because of the very size of the tank, homogenization is considerably retarded, particularly since the paddle or agitator has a tendency to create a vortex at the center of the tank. Because of the vortex relatively small quantities of fluid are subjected to a high speed blending action adjacent the vortex, while the larger quantities remote from the vortex are being rotated or blended at much lower speeds. Much of the energy imparted by the agitator or blending head to the fluid is thus inefliciently expended by the creation of the vortex; and the vortex in turn results in a non-uniform and slow rate of homogenization. Moreover, conventional homogenizing apparatus of the open, paddle tank type generally depend upon mere agitation or mixing of the fluid to produce a reduction in the size of the particles in the fluid. This process is therefore basically slow. If attempts are made to speed it up, they usually result in objectionable temperature rises within the homogenizing unit, as well as increasing wear and tear on the unit itself.

In the continuous-flow type homogenizing apparatus, usually a relatively small stream of fluid is continuously flowed past an agitator, thereby permitting a given small volume of fluid to be subjected to the agitator for a shorter period of time as compared to the open paddle-tank apparatus.

With conventional continuous-flow homogenizing apparatus, however, there is the disadvantage that although particle size and the uniformity thereof may be regulated by controlling the rate of flow of the fluid through the unit, it is often necessary, since most such units require pumping means separate from the homogenizing apparatus for pumping the fluid to the latter, to install additional means to regulate and coordinate the rate of flow of fluid through both the pump and the homogenizing apparatus. Moreover, conventional continuous-flow homogenizing units have been diflicult to assemble and clean.

A primary object of this invention is to provide homogenizing apparatus which will be more rapid and eflicient in operation than prior suoh apparatus.

Another object of this invention is to provide improved homogenizing apparatus which minimizes the creation of objectionable temperature rises in the fluid being homogenized.

Another object of this invention is to provide an improved homogenizing apparatus which uniformly distributes incoming fluid to the homogenizing elements so as to achieve greater uniformity in particle size.

A further object of this invention is to provide a homogenizing unit having means for recirculating fluid within the unit so as to achieve greater uniformity in particle size.

Another object of the invention is to provide homogenizing apparatus which incorporates both fluid pumping means and fluid homogenizing means in a single unit.

A still further object of the invention is to provide apparatus of the character described wherein the rate of flow of fluid through the unit and the uniformity of particle size is controllable by valve means positioned at the outlet of the unit.

Still another object of this invention is to provide a homogenizing unit having parts which are interchangeable and readily cleaned, and which is relatively small and compact, and capable of being efliciently operated by means of a relatively low horsepower motor.

Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims, particularly when read in conjunction with the accompanying drawings.

In the drawings:

FIG. 1 is a part side elevation, part section, showing a homogenizing unit made in accordance with one embodiment of this invention;

FIG. 2 is an enlarged sectional view taken along the line 22 in FIG. 1 and looking in the direction of the arrows;

P16. 3 is an enlarged fragmentary sectional view taken along the line 3-3 of FIG. 1 and looking in the direction of the arrows;

FIG. 4 is a side elevational view of the stator employed in this embodiment;

FIG. 5 is an exploded view showing in elevation a modified rotor and stator employable in place of those used in the embodiment illustrated in FIGS. 1 to 4; and

FIG. 6 is a sectional view taken along the line 6-6 of FIG. 5 and looking in the direction of the arrows.

Referring now to the drawings by numerals of reference, and first to the embodiment shown in FIGS. 1 to 4, 11 denotes a generally cup-shaped housing having an annular wall portion 12 and a closed end 13. Rotatably mounted in the closed end 13 is a shaft 21 which extends into the housing 11 coaxially of annular wall 12. Within housing 11 shaft 21 has a first reduced diameter portion 22 and a second further reduced diameter portion 24. The inner terminal end of the shaft is externally threaded as denoted at 26.

An impeller 31 is secured to shaft 21 to rotate therewith. The impeller 31 has an outside diameter slightly less than the inside diameter of annular wall 12. It is provided around its periphery with a plurality of equiangularly spaced notches 34 which define a plurality of impeller blades 35 for creating a primary centrifugal pumping effect in housing 11. Notches 34 are of relatively shallow radial depth and extend for only part of the axial length of the impeller, terminating short of the rear end of the impeller. Moreover, the sidewalls of each notch 34 are substantially parallel but inclined to the periphery of the impeller 31 in a direction opposite to the intended direction of rotation of the impeller as shown in FIG. 2.

Integral with the impeller 31 is an annular rotor 41. Rotor 41 extends forwardly from the front end of impeller 31 and terminates just short of the open end of the annular Wall 12 of housing 11. The outside peripheral surface of rotor 41 is at approximately the same radial distance from the axis of shaft 21 as the bottoms of the grooves 34 of impeller 31 and is therefore in line with these groove bottoms. Rotor 41 has a first plurality of short, parallel, angularly-spaced axiallyext-ending slots 42 and a plurality of equi-angularly spaced, longer, axially extending slots 45 through its annular wall. The slots 45 are out of axial alignment with slots 42 and spaced axially therefrom. As shown in FIG. 2, the side walls 43 of each slot 42 are disposed in parallel planes which are inclined in the direction of rotation of the rotor 41 (clockwise in FIG. 2). Slots 42 are thus inclined in the opposite direction to the notches 34 in the impeller 31. The side Walls 46 of each slot 45 are parallel planes and inclined in the same direction as are impeller notches 34. V

Disposed Within rotor 4-1, coaxially therewith is an rior of stator .69 and 'cooperate with the edges" of the circular apertures 65 in Stator 60 to shear the particles in agitator 51. Agitator 51 is threaded onto the threaded end 26 of shaft 21 to hold impeller 31 seated against the shoulder 52 formed on shaft 21 at the juncture of the first reduced diameter portion 22 of the shaft and the main. body of the shaft. As its rear end agitator 51 has a central boss 53 which engages a central boss 54 formed on the front face of impeller 31, thereby providing a space between the impeller and the agitator. two blades or vanes 55'extending outwardly from opposite sides of its hub 56, and offset from one another on op- The agitator has 7 posite sides of a diametralline passing through hub 56.

The front faces of the blades or vanes 55 are conical surfaces for the major portions of the length of the blades as denoted at 57; but the forward tip "surfaces of the blades are flat plane surfaces as denotedat 58. The hub 56 of the agitator is slabbed off on diametrically opposite sides as denoted at 59. :These'slab portions slope outi wardly rearwardly of the hub.

Interposed between the rotor 41 and an annular stator 60. The stator is integral with a circular cover plate 61' that is sealingly secured overthe theagitator 51 is the annular space 67. After being 'subjectedto such shearing operation, the fluid passes through rotor slots 45 which tend also to impart a slight centrifugal pumping effect to thefluid thereby further supplementing the pumping effect caused by the blades of impeller 31. Slots 42 of rotor 41, however, areinclined oppositely to slots and'impeller notches 34, andtend to force the fluid back into the interior of housing 11 thereby creating a recirculating effect. The recirculating effect tends to prolong the time in which a given volume of fluid is maintained within the housing 11; consequently increasing the through housing 11, assuming shaft 21 is revolved at a constant r.p.m.,. will depend, of'course, upon the extent to which the flow of fluid out throughduct 72 is restricted by the throttle valve placed in the outlet. The rate of flow of fluid through housing 11 will be maximum when I the valve is wide open and will be decreased proportionopen end of cup-shaped housing 11 by means of wing nuts 62. These nuts are threaded onto studs 63 that extend forward from annular wall 12. The cover plate 61 maintains stator in coaxial relation'with rotor 41 and agitator 51. The stator 60 extends at its rearend into a shallow recess 64 formed in the front face of impeller 31. The stator is provided with a plurality of spaced, helicallyarranged circular apertures 65 that extend through the annular wall of the stator. These connect the space 66 in the housing 11 between agitator 51 aud stator 6% with the space 67 betweenthe stator and rotor 41. The cover plate 61 has a centrally-disposed collar 68 projecting forwardfrom it. The bore of this collar provides the fluid inlet for the housing 11. The collar 68 is externally threaded for connection to the piping which delivers the fluid, that is to be treated, to the housing. r

Adjacent its closed end 13, annular wall 1270f housing 11 has an integral collar 71 projecting laterally there;

from. A port 72 is provided in wall 12 which is aligned fluid away from the housing. An adjustable throttlevalve 7 may be mounted incollar 71 or in the piping connected ately as the valve is throttled. If for some reason the throttle valve should be closed completely while fluid is in 7 housing 11, the recirculating effect created by the slots 42 will not only cause a greater reduction and greater uniformity in particle size, but will serve also to keep the fluidin thehousing 11 circulating so that undesirable temperature'rises'in thefluid will be avoided. Moreover,

by creating a recirculating effect when the flow rate to the pump housing 11 approaches zero, there is less tendency'on the part of the particles in the fluid to form undesirable concentrations in' anyone particular area in ,the housing 11.

' FIGS. Sand 6 illustrate modified rotary and stationary elements adapted to be employed in lieu of the rotary and stationary. elements illustrated'in the embodiment of FIGS. 1 to 4. Unlike the combined impeller 31 and rotor 41 shown in FIGS. 1 to 4, the rotary element 130 in 'FIGS..5 and 6 does'not have integral therewith an impeller for providing a primary centrifugal pumping elfect (such as impeller 31), butinsteadis adapted to be employed lI'l con unction with a separate pump disposed'externally 1 of the housing in which'the modified rotary element is thereto to control the rate of flow of the fluid from the housing.

In operation, with shaft 21 rotating at a constant rpm.

in the direction of arrow 74 in FIG. '2, fluid is sucked into housing 11 through the collar '68 on the cover plate 6l.

Rotating impeller blades 35 create a centrifugal pumping effect which draws the fluid from the collar through the apertures 65 in the stator 60, the annular space 67 between the stator 69 and rotor 41, through the elongate slots 45 I in rotor 41 into the annularspace 75 between the outer peripheral surface of rotor-41 and the inner surface of annular wall 12,,andinto the notches 34 of impeller 31;

Thence it is pumped outwardly through duct 72 and collar 71.

When fluid first enters housing 11, rotating agitator 51.

serves to initially blend the fluid and particles therein; and at the same time assists the centrifugalpumping eife'ct created by impeller 31. [Particularly when homogenizing 67, rotor slots 45 disrupt the film deposited on thejexte- 'mounted. However, it is to be understood that the modined elements in FIGS. 5 and 6 are adapted to be mounted in a housing identicalto that shown at 11 in FIGS. 1 to 4.

' The modified rotary element designated generally at comprises an axially bored disk portion 131 which has a smooth, conical, outer peripheral surface 132, a

central shallow, circular recess 133 in its rear face and a centr al circular boss 134 on its front face. Integral with disk portion 131, and projecting forwardly from the front facethereofisan annular rotor 141. Similar to rotor. 41, rotor 141 has two sets. of equiangularlyspaced and axiallyr'extending' slots through its annular Wall. The firstset of slots 142 are disposed in acircular path adjacent the frontend of the rotor wall. The second set of slots extends from a point adjacent disk por-- tion 131, axially of the rotor, to a point spaced axially rearwardly from the rear ends of slots 142. As in the caseof rotor 141, the slots 145 may be of the same numher and of the same angular spacing as the slots 142, but

. preferably are out of line axially with the slots 142. As

in: the case of rotor 41, also, the axial side walls 143 of slots 142 are inclined rearwardly from their outer to their inner ends to the direction of rotation ofrotor130, which is indicated by arrow 148;.while the sidewalls 146 of slots 145 are inclined from outer to inner ends in the opposite direction. r

As shown in FIG. 5, element 130 is adapted to be mounted on the end of a shaft 21 identical with that shown in FIGS. 1 to 4; and is adapted to be secured thereto by means of nut 151 and washer 152.

The modified stator designated generally at 161) comprises an axially bored circular cover plate 161 which is adapted to be secured over the open end of a housing of the type shown at 11 in FIG. 1. The cover plate 161 has a central annular boss 162 on its rear face adapted to fit snugly in the open end of such housing. Integral with boss 162 and extending coaxially rearwardly therefrom is an annular stator element 164 which is adapted to fit in radially spaced relation within the rotor 141, coaxially thereof, when the cover is secured over the open end of the housing. Stator element 164 has a plurality of spaced, helically-arranged, circular apertures 165 through its annular wall. The cover plate 161 has an integral collar 168 projecting forwardly from its front or outer face, thereby providing a duct for admitting fluid to the interior of stator 166. The apertures 165 are here larger in diameter than those in stator 60 of the first embodiment of the invention Moreover, the outside diameter of stator element 164 is preferably slightly less than the outside diameter of stator 60 so that when the former is inserted into rotor 141, which has an inside diameter comparable to that of rotor 41, there will be a larger radial spacing between the confronting peripheral surfaces of the elements 141 and 164 than between elements 41 and 60 of the first-described embodiment.

This increased radial spacing, and the greater diameter of the apertures 165 as compared to apertures 65, renders the modified rotary and stationary elements, 130 and 160 respectively, particularly adaptable to the homogenizing of fluids such as mayonnaise, salad dressing, cheese paste and the like by means of a whipping or texturizing action. Upon passing such fluids through the homogenizer housing, the large lumps therein are subjected to a whipping as well as shearing action as the fluid passes between the relatively large radial clearance between the stator element 164 and rotor 141, and is thereafter subjected to polishing or texturizing operation as it passes over the conical surface 132 on disk 131 on the Way out of the housing.

As in the case of the embodiment illustrated in FIGS. 1 to 4, the slots 145 in rotor 141 are adapted to be rotated in a direction which will cause them to impart a radially outwardly centifugal pumping effect to the fluid in the housing to supplement the head created by a pump at the housing exterior. Slots 142, inclined oppositely to slots 145, will thus create a recirculating effect by forcing fluid radially inwardly from the exterior of rotor 141.

Each of the novel stators 60 and 160 performs the dual function of screening and distributing the incoming fluid. Particles cannot pass into the annular space between the rotor and stator until they have been reduced to a predetermined maximum particle size; a size depending upon the diameters of the helically disposed holes in the respective stators. (This initial reduction in particle size is produced principally by the agitator 51 in the first embodiment (FIGS. 1 to 4) and by extrusion through the stator holes 165 in the case of the second (FIGS. 5 and 6) embodiment.) Upon passing through the annular wall of stator 60 or 169, the helically disposed holes 65 or 165 positively distribute the fluid uniformly along the axial length of the space between rotor and stator. Such liquid flow control prevents excessive volumes of fluid from passing through the annular wall of the rotor at any one particular point, thereby making more eflicient use of the shearing action which occurs between the rotor and stator; and resulting in a greater rate of attrition in the prdouct being homogenized. Moreover, by using circular apertures in the stators of the type disclosed herein, the particles in the liquid passing through the apertures and into the path of the rotating rotor are first subjected to compressive forces caused by the extruding effect of the apertures, and thereafter to further compressive forces of implosion resulting from the cavitation effect produced when the rotor is rotated at high speeds relative to the stator. Such forces tend to cause a reduction in particle size which supplements the particle size reduction caused by the positive shearing effect which the confronting marginal edges of the holes and slots in the stator and rotor produce, upon being moved relative to one another. It will be seen, therefore, that both embodiments of the invention operate with high eficiency and fast.

While the invention has been described in connection with two specific embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention or the limits of the appended claims.

Having thus described my invention, what I claim is:

1. Homogenizing apparatus comprising a housing, a plurality of annular elements mounted in said housing in coaxial, radially-spaced relation, one of two radially adjacent elements having a plurality of identically-shaped apertures therethrough equally spaced from one another axially, the other of said two elements having a plurality of circuferentially spaced axially-extending slots therethrough, means for effecting relative rotation between said two elements, said housing having inlet and outlet ports at raidally opposite sides of said elements for admitting fluid to and exhausting it from said housing, and means for directing incoming fluid successively through said apertures, said slots, and said outlet port, whereby upon relative rotation between said two elements and the passage of fluid through said housing, said apertures in said one element evenly distribute said fluid along the axial length of the radial space between said two elements, and the confronting marginal edges of said apertures and slots, respectively, cooperate to shear the fluid in the radial space between said two elements.

2. Homogenizing apparatus as claimed in claim 1 wherein said apertures are circular and are disposed in a helical path extending about the axis of said one element.

3. Homogenizing apparatus comprising a housing, a plurality of annular elements mounted in said housing in coaxial, radially-spaced and substantially axially-coexten sive relation, the radially-outermost of said elements and the confronting wall of said housing also being radially spaced from one another and defining therebetween an annular chamber, said housing having an inlet duct communicating with the interior of the radially innermost of said elements, said housing having an outlet duct communicating with said chamber, said annular elements having a plurality of radially-extending apertures through their annular walls, drive means for effecting relative rotation between two of said elements disposed radiallyadjacent to one another, the apertures in the radiallyinnermost of said two elements being circular openings of equal diameter equi-spaced from one another along a helical path extending about the axis of the last-named element, and the apertures in the other of said two elements comprising circumferentially spaced axially-extending slots disposed intermediate the ends of said other element, whereby upon relative rotation between said two elements and the pumping of fluid through said housing, said circular apertures evenly distribute said fluid along the axial length of the radial space between said two ele ments, and the confronting marginal edges of said circu lar apertures and slots, respectively, cooperate to shear particles contained in the fluid in the last-named radial space.

4. Homogenizing apparatus as claimed in claim 3 wherein there are at leasttwo axially-spaced groups of said slots in said other element, the axially-extending sidewalls of each slot in one of said two groups being plane,

parallel surfaces and being inclined radially in one 'di' rection -relative to the circumference ofsaid other ele-' ment, the axially-extending sidewalls of each slot in the other of said two groups being plane, parallel surfaces, and being inclined radially in the opposite direction relative to saidcircumference, and the axial length of the slots in one'of said two groupsbeing substantially great;

er than the axial length of the slots in'the other of said as claimed inclaim 3 havpumped by said'impeller-from said chamber through b said outlet duct.

6. Homogenizing apparatuses claimed in claim hav ing a rotary fluid agitator mounted within the'interior of said innermost element which has two blades extending radially outwardly thereof toward thesinner peripheral surface of said innermost element said blades being radially oifset on opposite sides of an axial plane of said said housing adjacent said one end wall thereof, means removably securing said eleinent to said shaft, astation: ary, annular element secured to the opposite end wall of said housing and extending therefrom into said housing toward said disk coaxially of said shaft, a rotatable, annular element secured at one end to the face of said disk-shaped element remote from said one end wall of comprising a housing, a

circumference.

' e a a peripheral surface, said notehes having the axially-extending sidewalls thereof inclined radially relative to its ltLHomogenizing apparatus as claimed in claim 9 wherein there'areat least two axially-spaced groups of said slots in said rotatable element, the axially-extending sides ofthe slots in one of said two groups being inclined relative to said circumference in the same direction as the inclined sidewalls of said notche s, and the axially-extending sidewalls of the slots in the other of said two, groups being inclined relative'to said circumference in the opposite direction,-whereby upon rotation of said disk-shaped element and of saidlrotatableelement, said one group of slots tend to supplement the centrifugal pumping effect .of said disk-shaped element, and. said slots of said other group urge fluid radiallyinw-ardly of said annular elements to create a recirculating effect in said housing.

11. Homogenizing apparatus .as claimed in claim 7 wherein said securing means comprisesan agitator having a hub portion secured to said shaft, and two diametrally oppositeblades integral with said hub portion and extending outwardly therefrom toward the innerperipheral surface of said stationary element, said blades being radially ofi'set on opposite sides of an axialplane of said agitator. 7 V

12. Homogenizing apparatus comprising a housing closed at one end and open at its other end, a cover secured to said housing to close said-other end of said housing, a shaft extending through-said closed end into saidhousingQa'purnp element secured to said shaft within'said housing to rotate with said shaft, a first shearing member secured to said pump element to rotate there- 'with and having an annular wall having a' plurality of the first-named annular wall, the second-named annular said housing and extending therefrom toward said op posite end wall coaxially of and inradially-spacedrela-J tionabout, and substantially axially coextensive with said stationary element, the annular Wall of said stationay element having therethrough intermediate the; ends thereof, a plurality of spaced, identical apertures disposed in a helical path, and the annular wall of said rotatable element having intermediate the ends thereof a'plurality of circumferentially spaced and axially-extending slots therethrough, said opposite end wall of said housing having an inlet port therethrough communicating with the intewall being substantially coextensive lengthwise with said first-narned annular wall and having a plurality of apertures therethrough, which are equi-spaced axially from one another and disposed helically' about the common axis of said annular walls, and means for admitting fluid to and exhausting-it from said housing.

13. Homogenizing apparatus as claimed in claim 12,

wherein said first shearing memberhas two groups of longitudinal slots therethrough,]the slots of one group being spaced from the slots of the other group longitudinally ofsaid first shearing memben'theside walls of s the other group'being inclinded in the opposite direction rior of said stationary element, said housing having an I outlet'port disposed radially outside of said rotatable element, whereby upon the rotation of said shaft fluid is' caused to flow radially outwardlythrough the annular walls of said stationary and. rotatable elements'to. said V wherein said first shearing member has two groups of outlet duct and said helically disposed apertures evenly distribute incoming fluid' along the'axialle'ngth of, the

radial space between said stationary and rotatable 'ele merits, and the marginal edges of said apertures and rotating slots, which confront the radial space between said 7 with reference to said radial planes, and said pump element has a plurality of angularly-spaced, longitudinallyextending grooves in its outer peripheral surface, the side walls of which are also inclined to said radial Planes.

14. Homogenizing apparatus as claimed in claim 12,

longitudinal slots therethrough, the slots of one group being spaced from the slots of thenother group longitudinally of said first shearing member, the side walls of each of the slots of one group being inclined in'one direction with reference to radial planes ofsaid first shearouter peripheral surface which converges inwardly from said one end wall of said housing and merges with the outer peripheral surface of said rotatable element, said outlet port being disposed adjacent said outer conical surface whereby before leaving said housing, fluid is caused to pass over said conical surface. 1 I

9. Homogenizing apparatus as claimed in claim 7 wherein said disk-shaped element has a plurality of ax-' ially-extending equi-angularlyspaced notches in itsouter port, and said pump element has a smooth conical peripheral surface disposed close to the confronting inside wall of said housing and disposed so that fluid must pass thereover in. its'flow to said outlet port. 7

15, Homogenizing apparatus as claimed in claim 13 having a multi-bladed'agitator secured to said shaft in abutting relation to said pump element and radially withadjacent thereto.

References ited by the Examiner UNITED STATES PATENTS 7/ 10 Damon.

10 Nicol.

Ditto 259-9 Keen 259-7 X Hofmann 259-7 X McDonald 259-96 Wallinson et a1. 241255 \VALTER A. SCHEEL, Primary Examiner. 

1. HOMOGENIZING APPARATUS COMPRISING A HOUSING, A PLURALITY OF ANNULAR ELEMENTS MOUNTED IN SAID HOUSING IN COAXIAL, RADIALLY-SPACED RELATION, ONE OF TWO RADIALLY ADJACENT ELEMENTS HAVING A PLURALITY OF IDENTICALLY-SHAPED APERTURES THERETHROUGH EQUALLY SPACED FROM ONE ANOTHER AXIALLY, THE OTHER OF SAID TWO ELEMENTS HAVING A PLURALITY OF CIRCUMFERENTIALLY SPACED AXIALLY-EXTENDING SLOTS THERETHROUGH, MEANS FOR EFFECTING RELATIVE ROTATION BETWEEN SAID TWO ELEMENTS, SAID HOUSING HAVING INLET AND OUTLET PORTS AT RADIALLY OPPOSITE SIDES OF SAID ELEMENTS FOR ADMITTING FLUID TO AND EXHAUSTING IT FROM SAID HOUSING, AND MEANS FOR DIRECTING INCOMING FLUID SUCCESSIVELY THROUGH SAID APERTURES, SAID SLOTS, AND SAID OUTLET PORT, WHEREBY UPON RELATIVE ROTATION BETWEEN SAID TWO ELEMENTS AND THE PASSAGE OF FLUID THROUGH SAID HOUSING, SAID APERTURES IN SAID ONE ELEMENT EVENLY DISTRIBUTE SAID FLUID ALONG THE AXIAL LENGTH OF THE RADIAL SPACE BETWEEN SAID TWO ELEMENTS, AND THE CONFRONTING MARGINAL EDGES OF SAID APERTURES AND SLOTS, RESPECTIVELY, COOEPRATE TO SHEAR THE FLUID IN THE RADIAL SPACE BETWEEN SAID TWO ELEMENTS. 